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Thermodynamic Regulation of Actin Polymerization



P S. Niranjan, J G. Forbes, S C. Greer, J Dudowicz, Karl Freed, Jack F. Douglas


A Flory-Huggins-type lattice model of actin polymerization under equilibrium conditions is employed to analyze new spectroscopic measurements for the extent of actin polymerization diameter} as a function of temperature T, salt concentration [KC1], and the initial concentration of actin monomers [Go]. The theory subsumes existing mechanisms for actin monomer initiation, dimerization, and chain propagation. The extent of polymerization diameter} increases with T to an unanticipated maximum, and the calculations explain this unusual effect as arising from a competition between monomer activation, which diminishes upon heating, and propagating chain growth, which increases upon heating. The actin polymerization is described as a rounded phase transition, and the associated polymerization temperature Tp depends strongly, but nearly linearly on [Go]and [KC1] over the concentration regimes investigated. Our findings support the suggestion that physicochemical changes can complement regulatory proteins in controlling actin polymerization in living systems.
Journal of Chemical Physics
No. 24


Flory-Huggins-type lattice model


Niranjan, P. , Forbes, J. , Greer, S. , Dudowicz, J. , Freed, K. and Douglas, J. (2001), Thermodynamic Regulation of Actin Polymerization, Journal of Chemical Physics, [online], (Accessed April 13, 2024)
Created May 31, 2001, Updated October 12, 2021